Contours of X‐ray surface brightness (3, 6, 9, 12, and 15 σ above background) in NGC 4038/39 superposed on (a) I‐band and (b) U‐band (near‐ultraviolet) CCD images kindly provided by P. Seitzer. Registration between X‐ray and CCD images was achieved as described in text. The X‐ray data have been binned into 1^{﹩\arcsec﹩} pixels and smoothed with a Gaussian of σ = 2^{﹩\arcsec﹩}. X‐ray sources of Table 1 are identified in (b).